The present invention relates generally to a soft lining material for the mucosal-side surfaces of resin or metal dentures, and more particularly to a soft lining material composition for dentures, which is used for the purpose of relieving those who have dentures of pain and improving the suction of dentures.
Those who have dentures over an extended period of time often suffer from the adsorption of bones and the thinning of mucosae. In such cases, the dentures, because of being formed of resin and hard material such as metal, abut on the surrounding portion of the highest site of the bone during mastication, causing pain to the patients. With a periostitic patient, the alveolar bone processes are found or the alveolar bones are adsorbed to lower the alveolar ridges. In such cases, a undue pressure is applied on the site of the alveolar bone process during mastication, causing pain.
In serious cases caused by problems ascribable to mucosae and bones, there is no choice but to continuously use soft lining materials, except the cases where dentures are fixed with implants.
Currently available such soft lining materials are based on acrylic resins, fluorocarbon resins, polyolefin resins, and silicone resins. However, the acrylic resin type of soft lining shows good adhesion to dentures, but it cannot be used over an extended period of time because its elasticity vanishes rapidly within several weeks due to the oozing-out of plasticizers, etc. The fluorocarbon resin type of soft lining material is limited in terms of water absorption and oozing-out. However, this is not only less effective for relieving pain but also has difficulty in use because of involving awkward dental operations. The polyolefin resin type of soft lining material, albeit being excellent in elasticity, has difficulty in use because of involving very awkward dental operations through which polymerization by heating is carried out with the use of two adhesive materials. The silicone resin type of soft lining material can be used directly in the mouth and so can be handled with ease. A typical silicone resin type of soft lining material disclosed in Japanese Laid-Open Patent No. 7-41411 is characterized by the incorporation of a polyorganosylsesquioxane filler, and is excellent in resistance to coloration and the ability to be cut. However, problems with these silicone resin type of soft lining materials are that, while used in the mouth over an extended period of time, they become brittle with a visco-elasticity drop, and so lose their action on relieving pain. Further, they have a little adhesive strength with respect to a denture, and so often separate away from the denture. Furthermore, they are poor in the ability to be cut and polished, and become often unfit for dentures due to difficulty in post-curing correction of morphology.
Thus, currently available soft lining materials tend to become brittle with a viscoelasticity drop while they are used over an extended period of time, and so lose their initial effect on relieving pain. For this reason, they are still less than satisfactory for those who suffer from pain caused by such changes as mentioned above. Many of the current soft lining materials take long to produce because of involving awkward dental operations such as polymerization-by-heating operations. Further, they are poor in the ability to be cut and polished, and become unfit for dentures because of difficulty in post-curing correction of morphology. Further-more, such problems may be solved by cost-intensive materials. However, they are practically unacceptable; it is one necessary requirement that they can be produced at relatively low cost.
A primary object of the present invention is to provide a soft lining material composition for dentures, which is substantially free from the problems such conventional soft lining materials have involved.